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20. Subtracting Fractions example ( Enter your problem )

1. Example-1





1. Find `3/4 - 1/2`

Solution:
`=(3)/(4) - (1)/(2)`

LCM of `4,2` is `4`


Step-1: Prime factorization of `4,2` using factor by division method

24
22
 1
 
22
 1

Step-2: Write each number as a product of primes, matching primes vertically when possible
4=2 × 2
2=2

Step-3: Bring down the primes in each column. The LCM is the product of these factors
4=2 × 2
2=2

LCM = 2 × 2 = 4

`:.` LCM of `4,2` is `4`


`=(3)/(4) - (1 xx 2)/(2 xx 2)` (Change into equivalent fractions with the LCD 4)

`=(3)/(4) - (2)/(4)` (Simplify the numerators and denominators)

`=(3 - 2)/(4)`

`=(1)/(4)`
2. Find `3/4 - 5/6`

Solution:
`=(3)/(4) - (5)/(6)`

LCM of `4,6` is `12`


Step-1: Prime factorization of `4,6` using factor by division method

24
22
 1
 
26
33
 1

Step-2: Write each number as a product of primes, matching primes vertically when possible
4=2 × 2
6=2 × 3

Step-3: Bring down the primes in each column. The LCM is the product of these factors
4=2 × 2
6=2 × 3

LCM = 2 × 2 × 3 = 12

`:.` LCM of `4,6` is `12`


`=(3 xx 3)/(4 xx 3) - (5 xx 2)/(6 xx 2)` (Change into equivalent fractions with the LCD 12)

`=(9)/(12) - (10)/(12)` (Simplify the numerators and denominators)

`=(9 - 10)/(12)`

`=(-1)/(12)`
3. Find `5/6 - 1/6`

Solution:
`=(5)/(6) - (1)/(6)`

`=(5 - 1)/(6)`

`=(4)/(6)`

Reduce fraction
`=(2)/(3)`
4. Find `1/2 + 3/4 - 5/6`

Solution:
`=(1)/(2) + (3)/(4) - (5)/(6)`

LCM of `2,4,6` is `12`


Step-1: Prime factorization of `2,4,6` using factor by division method

22
 1
 
24
22
 1
 
26
33
 1

Step-2: Write each number as a product of primes, matching primes vertically when possible
2=2
4=2 × 2
6=2 × 3

Step-3: Bring down the primes in each column. The LCM is the product of these factors
2=2
4=2 × 2
6=2 × 3

LCM = 2 × 2 × 3 = 12

`:.` LCM of `2,4,6` is `12`


`=(1 xx 6)/(2 xx 6) + (3 xx 3)/(4 xx 3) - (5 xx 2)/(6 xx 2)` (Change into equivalent fractions with the LCD 12)

`=(6)/(12) + (9)/(12) - (10)/(12)` (Simplify the numerators and denominators)

`=(6 + 9 - 10)/(12)`

`=(5)/(12)`




This material is intended as a summary. Use your textbook for detail explanation.
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